Scabies, caused by the ectoparasitic mite, Sarcoptes scabiei, is an important highly contagious skin disease of humans. Worldwide, 300 million persons are infested with scabies at any time and in some countries nearly 100% of infants and >50% of older children and women have the disease. Scabies persists despite the availability of acaricides. One long-term objective will be to characterize scabies antigens and determine the host immune response mechanisms to these antigens. This research is a prerequisite to the eventual production of relevant antigens by recombinant DNA techniques and development of a vaccine for immunization of susceptible populations for the global control of scabies. A second long-term objective is to investigate the immune mechanisms, host parasite interaction, and mite biology in order to understand factors that influence the epidemiology and pathology of the disease. Specifically: one aim will be to isolate and characterize the relevant antigens of S. scabiei. These studies will provide an understanding of antigen structure and the molecular basis for immune recognition of the antigens. Column chromatography, HPLC, IEF, SDS-PAGE, CIE, CRIE and immunoblotting will be used to isolate the antigens from whole extracts and to physicochemically and immunologically characterize them. Second, the study will determine the cell-mediated and humoral response mechanisms to scabies antigens and bioassay the expression of resistance to scabies mites for naive and sensitized hosts. Controlled studies of the sequential quantitative histological changes in the areas of scabietic lesions coupled with serum antibody analyses and targeted manipulation of some immune processes will be done. The cell-mediated mechanism responsible for induced resistance will be elucidated. Many scabies mite antigens are highly cross-reactive with house dust mite antigens. Because of this cross-reactivity, a third aim will be to determine if immunization with dust mite antigens will induce immunity to scabies. This will be accomplished by comparing the sequential quantitative histology and expressed resistance of scabies sensitized and house dust mite immunized hosts. Fourth, the study will characterize the pathophysiology and histopathology in parasitized natural hosts to establish how scabies affects the health of the host. This will be accomplished by investigating hematology, blood biochemistry and organ histology. Fifth, using choice-bioassays, pheromones (guanine) and other interactions with host skin factors (skin lipids) will be investigated to determine that factors mediate assembly of mating pairs, determine host specificity, survival, and direct mites to specific body areas.